Motors are used in various kinds of applications. Electric power is supplied to a motor via a power supply cable. To secure safety in connection and disconnection of the power supply cable during maintenance and inspection of the motor, an interlock mechanism is provided. In Patent Literature 1, an interlock connector is provided between a removable lid and a casing of a high pressure unit, with the removal lid serving to check the operation of the high pressure unit, whereby power supply can be cut off by the interlock connector by removing the removable lid.